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Topology optimization of an acoustic diode?
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. (Design Optimization Group)ORCID-id: 0000-0002-3800-6438
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
2021 (Engelska)Ingår i: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 63, nr 6, s. 2739-2749Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

By using topology optimization, we consider the problem of designing a passive acoustic device that allows for one-way flow of sound waves; such a device is often colloquially referred to as an acoustic diode. The Helmholtz equation is used to model the time harmonic linear wave propagation together with a Dirichlet-to-Neumann (DtN) type boundary condition, and the finite element method is used for discretization. The objective of this study is to maximize the wave propagation in one direction (from left to right) and minimize the wave propagation in the reverse direction (from right to left) for planar incoming waves. The method of moving asymptotes (MMA) solves the optimization problem, and a continuation approach is used for the penalizing intermediate design variables. The results for the optimized waveguide show that more than 99.8% of the power of planar incoming waves get transmitted from left to right while less than 0.3% gets transmitted in the reverse direction for planar incoming waves in the specified frequency range. Since a true diode is a non-reciprocal device and here we used a linear acoustic wave model, which is basically reciprocal, we discuss details about how it appears to be possible to obtain a one-way waveguiding effect using this linear model.

Ort, förlag, år, upplaga, sidor
Springer, 2021. Vol. 63, nr 6, s. 2739-2749
Nyckelord [en]
Helmholtz equation, topology optimization, acoustic diode
Nationell ämneskategori
Beräkningsmatematik
Forskningsämne
numerisk analys
Identifikatorer
URN: urn:nbn:se:umu:diva-179740DOI: 10.1007/s00158-020-02832-9ISI: 000615764500003Scopus ID: 2-s2.0-85100577809OAI: oai:DiVA.org:umu-179740DiVA, id: diva2:1526967
Tillgänglig från: 2021-02-09 Skapad: 2021-02-09 Senast uppdaterad: 2023-09-05Bibliografiskt granskad
Ingår i avhandling
1. Material distribution-based topology optimization for wave propagation problems
Öppna denna publikation i ny flik eller fönster >>Material distribution-based topology optimization for wave propagation problems
2022 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Alternativ titel[sv]
Materialdistributionsbaserad topologioptimering för vågutbredningsproblem
Abstract [en]

This thesis employs material distribution-based topology optimization for wave propagation problems. In the material distribution approach, we define a material indicator function that models the presence and absence of material in a design domain. By placing material inside the design domain, the aim is to design a device that maximizes the output power or transmission of the system. The time-harmonic linear wave propagation problem is modeled using the Helmholtz equation. The governing equation is solved using the finite element method, and an artificial boundary condition is used to truncate the domain. Moreover, a gradient-based algorithm, the method of moving asymptotes by Svanberg, is used to solve the optimization problem. An adjoint method efficiently computes the gradients of the objective function with respect to design variables. 

This thesis considers two types of wave propagation problems: acoustic (Papers I-III) and electromagnetic wave propagation (Papers IV-V). In Papers I-II, we consider a bandpass design of a subwoofer. The aim of Paper I is to reduce the computational time required to evaluate the performance of a given subwoofer layout. To accomplish this, we develop a computationally efficient hybrid 2D-3D model. A full 3D model, as well as a lumped model, validate the hybrid model's results. Paper II focuses on optimizing the topology of a subwoofer using the computationally efficient hybrid model from Paper I for single as well multiple frequencies. In Paper III, we design a highly efficient uni-directional linear acoustic waveguide. Moreover, we also challenge the use of the term acoustic diode for such uni-directional linear acoustic waveguides in literature. Paper IV deals with the design of a microwave frequency dividing multiplexer, which splits the incoming signals into two frequency bands and delivers them to their respective output ports. In Paper V, we use the adjoint method to perform the sensitivity analysis of a coupled plasmonic problem where a Helmholtz equation is coupled to the Poisson equation. We validate the sensitivities computed using the adjoint method with the finite difference approach.

Ort, förlag, år, upplaga, sidor
Umeå: Umeå University, 2022. s. 36
Serie
Report / UMINF, ISSN 0348-0542 ; 22.05
Nyckelord
topology optimization, material distribution, wave propagation problems, Helmholtz equation, acoustics, electromagnetics, plasmonics
Nationell ämneskategori
Beräkningsmatematik
Identifikatorer
urn:nbn:se:umu:diva-193444 (URN)978-91-7855-749-3 (ISBN)978-91-7855-750-9 (ISBN)
Disputation
2022-04-28, NAT.D.320, Umeå University, Umeå, 13:15 (Engelska)
Opponent
Handledare
Tillgänglig från: 2022-04-07 Skapad: 2022-04-01 Senast uppdaterad: 2022-04-04Bibliografiskt granskad
2. Computational analysis and design optimization for acoustic devices
Öppna denna publikation i ny flik eller fönster >>Computational analysis and design optimization for acoustic devices
2023 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis focuses on material distribution topology optimization for acoustic waveguides. The limitations of the material distribution approach are discussed in the context of acoustic waveguides with extensive viscous and thermal boundary losses. An extension of the material distribution method is introduced which is capable of incorporating these boundary losses in the optimization process. Furthermore, a computational analysis of waveguide acoustic black holes (WABs) is also provided followed by a topology optimization approach for the conceptual design of a WAB with enhanced wave-focusing capabilities, utilizing the novel method introduced in the first part of the thesis.  The thesis commences with a comprehensive literature review to set the context for the subsequent research. The material distribution topology optimization is then discussed in detail, focusing on the design of a transition section for impedance matching between two cylindrical waveguides with different radii to maximize planar wave transmission. The linear wave propagation in the device is modeled using the Helmholtz equation and solved utilizing the finite element method to obtain acoustic pressure distribution. Nonlinear density filters are used to impose a size control on the design, and the design optimization problem is formulated and solved utilizing the method of moving asymptotes (MMA) with the sensitivity information provided through an ad-joint method. Selected results are provided for the considered design optimization problem. We expanded the analysis to encompass viscothermal acoustics and introduced a novel material distribution method capable of incorporating complex interface conditions. The new method is then applied to design acoustic absorbers with the aim of maximizing boundary losses in a targeted frequency range. The selected results represent the effectiveness of the proposed method.  The thesis further explores the limitations of the classical ribbed design of WABs in achieving true wave-focusing capabilities. To address this, a design optimization problem is formulated to obtain a conceptual design of a WAB. Utilizing the novel material distribution method for viscothermal acoustics introduced in this thesis, the optimization problem is solved, and the optimized design is compared with the results of a classical lossless approach and the ribbed design WAB. The numerical simulations demonstrate the superior wave-focusing capabilities of the optimized design, especially when incorporating boundary losses in the optimization process.   

Ort, förlag, år, upplaga, sidor
Umeå: Umeå University, 2023. s. 57
Serie
Report / UMINF, ISSN 0348-0542 ; 23.05
Nyckelord
Design optimization, computational analysis, viscothermal acoustics, material distribution topology optimization, acoustic black holes, finite element method
Nationell ämneskategori
Strömningsmekanik och akustik
Identifikatorer
urn:nbn:se:umu:diva-214089 (URN)978-91-8070-146-4 (ISBN)978-91-8070-147-1 (ISBN)
Disputation
2023-09-29, NAT.D 300, Naturvetarhuset, Umeå, 09:15 (Engelska)
Opponent
Handledare
Tillgänglig från: 2023-09-08 Skapad: 2023-09-04 Senast uppdaterad: 2023-09-05Bibliografiskt granskad

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